This proposal requests funds to help purchase a high resolution mass spectrometer as a research resource at the University of Texas Health Science Center at Houston. This equipment will be used to support current NIH funded research programs almost exclusively. The spectrometer would be located, maintained, operated and administered in the Analytical Chemistry Center, the University of Texas Medical School at Houston. The Center is a bio-analytical research resource, set up and supported by the Medical School, which provides both modern analytical instrumentation to research investigators and staff who can use this technology expeditiously. The proposed users of the mass spectrometer are divided into three groups. The primary users consists of Richard M. Caprioli (structure of modified proteins), Finn Wold (protein structure and function), Peter Berget (structure of phage tail proteins), Roger Lester and Jan Pyrek (metabolism of bile acids of humans), and James Chambers and Julian Williams (structure of oligosaccharides from lysosomal enzymes). These users would account for approximately 75% of the available instrument time. The secondary user group consists of John DeMoss (structure of fragment of nitrate reductase), Rodney Howell (detection of inborn metabolic disorders), Joachim Liehr (estrogen-induced carcinogenesis), Ron Smith (pharmacology of anti-tumor agents) and Jack Henkin (synthesis of anti-folates). The remaining 15% time will be available for general use by the surrounding community of research investigators. The Analytical Chemistry Center will maintain and operate the instrument throughout its useful life in the scientific community.